Note that you better not open any executable attachments (.scr .exe .pif etc.) even though the sender might be someone you know - your mom, boss hey it can even be Toby!

Keep your anti-virus program updated (or get a non-MS operating system). Oh and since there are also more and more nasty worms spreading wildly these days, you better also get a personal firewall. There are also several free personal firewalls available so you shouldn't have any excuse for not using one.